Implant sensors

Abstract

Exemplary orthopedic implants are disclosed. The orthopedic implants may include one or more sensors. Exemplary sensors include sensors to monitor bone growth, changes to the implant over time, and proper placement of the implant. The orthopedic implants may include a woven material. Sensor arrangements to detect a state of an item are disclosed. Exemplary states include folded, unfolded, and inflated. Exemplary items include an orthopedic implant and a parachute.

1. An orthopedic implant for placement in a cavity formed in a bone, said cavity having a predetermined shape, said orthopedic implant comprising:
 a flexible body having an opening, said flexible body having an inflated state wherein said body has an outer shape generally corresponding to said predetermined shape formed in said bone and a non-inflated shape wherein said outer shape has a smaller envelope than said inflated state; 
 a plurality of sensors supported by said flexible body, said plurality of sensors providing an indication of whether said flexible body is in said inflated state or said non-inflated state, wherein said plurality of sensors are configured to detect a presence of a fold in said flexible body, wherein said fold is detected based on said relative position of a first sensor to a second sensor, wherein said first sensor and said second sensor are passive sensors interrogated by an external device, wherein said first sensor and said second sensor are each resonant circuits which provide said indication based on a separation between said first sensor and said second sensor, and wherein when said first sensor and said second sensor are spaced a first distance apart said first sensor resonates in response to a first frequency from said external device and said second sensor resonates in response to a second frequency from said external device and when said first sensor and said second sensor are spaced less than said first distance apart said first sensor and said second sensor resonate together in response to a third frequency from said external device; and 
 a filler, said filler being positioned in said flexible body and causing said flexible body to transition from said non-inflated state to said inflated state. 
 
     
     
       2. The orthopedic implant of  claim 1 , wherein said filler is a polymer based material. 
     
     
       3. The orthopedic implant of  claim 1 , wherein said external device interrogates said plurality of sensors through a frequency range including said first frequency, said second frequency, and said third frequency. 
     
     
       4. A method of implanting an orthopedic implant in a cavity having a predetermined shape formed in a bone, said method comprising the steps of:
 providing a flexible body which is inflatable to a first state having an outer shape generally corresponding to said predetermined shape formed in said bone; 
 positioning said flexible body in said cavity having said predetermined shape formed in said bone; 
 inflating said flexible body; and 
 sensing whether said flexible body is inflated to said first state, including the steps of:
 providing a plurality of passive sensors supported by said flexible body; 
 interrogating said plurality of passive sensors to determine whether said flexible body is inflated to said first state, including the steps of:
 passing a first plurality of radio frequency frequencies through said bone; 
 receiving a second plurality of radio frequencies from said plurality of sensors; and 
 determining whether said flexible body is inflated to said first state based on said received second plurality of radio frequencies. 
 
 
 
     
     
       5. The method of  claim 4 , wherein said step of inflating said flexible body includes filling an interior of said flexible body with a filler which hardens over time. 
     
     
       6. A woven material for use within the body, the woven material comprising:
 a first woven layer having a first plurality of weft fibers and a first plurality of in layer warp fibers, said first layer having a first stiffness; 
 a second woven layer having a second plurality of weft fibers and a second plurality of in layer warp fibers, said second layer having a second stiffness generally less than said first stiffness; 
 a third woven layer having a third plurality of weft fibers and a third plurality of in layer warp fibers, said third layer having a third stiffness generally less than said second stiffness; 
 a first plurality of out of layer warp fibers which couple together said first layer and said second layer; 
 a second plurality of out of layer warp fibers which couple together said second layer and said third layer 
 a fourth layer having a fourth stiffness and coupled to said third layer opposite said second layer; 
 a fifth layer having a fifth stiffness and coupled to said fourth layer opposite said third layer; 
 a third plurality of out of layer warp fibers which couple together said third layer and said fourth layer; and 
 a fourth plurality of out of layer warp fibers which couple together said fourth layer and said fifth layer, 
 wherein said first plurality of weft fibers and said first plurality of in layer warp fibers are metallic fibers and wherein said second plurality of weft fibers and said second plurality of in layer warp fibers are a blend of metallic fibers and non-metallic fibers. 
 
     
     
       7. The woven material of  claim 6 , further comprising a fourth layer having said first stiffness and coupled to said first layer opposite said second layer. 
     
     
       8. The woven material of  claim 6 , wherein said third plurality of weft fibers and said third plurality of in layer warp fibers are polymeric fibers and wherein said blend includes and polymeric fibers. 
     
     
       9. The woven material of  claim 6 , wherein at least one of said first layer, said second layer, and said third layer support a plurality of sensors. 
     
     
       10. The woven material of  claim 9 , wherein said plurality of sensors provide an indication of a shape of the woven material. 
     
     
       11. The woven material of  claim 6 , wherein said plurality of sensors are passive radio frequency sensors.